Propagation of neuronal signals in intact and injured peripheral nerves: The role of nonlinear diffusion of transmembrane potential

Abstract

We present results of a computational study of the influence of nonlinear diffusion on propagation of electrical excitation generated in normal and injured peripheral nerves (PN) using a one-dimensional Fitzhugh-Nagumo (FN) model. Changes in action potential duration (APD) and repolarization intervals (RI) were observed based upon modification of the FN model. Namely, the model has been altered by adding an additional power function type nonlinear diffusion term which accounted for substantial intra-extracellular charge balance changes developing during action potential formation in small peripheral nerves. It was found that changes in magnitude of nonlinear diffusion coefficient result in oscillations of APD and RI in both normal and injured PNs with partially reduced conductivity. It was also found that these oscillations in injured PNs had markedly higher amplitudes dependent on the PN's length as well as on the width of its injured part. Results of our study may be useful in improving of monitoring of peripheral nerve growth and adjusting propagation of excitation to enhance impaired connectivity in injured peripheral nerves.